Angular rate sensor having a vibration gyroscope

ABSTRACT

The invention relates to an angular rate sensor having a vibration gyroscope, in which circuits are provided for operating the vibration gyroscope and for deriving an angular rate signal. Said circuits access modifiable data, whereby this data is stored in a writable non-volatile memory. Means are provided for reading out the data from the non-volatile memory after the angular rate sensor is switched on.

The invention relates to a rotation rate sensor having a vibration gyro,in which circuits which access variable data are provided for operationof the vibration gyro and for emission of a rotation rate signal.

By way of example, EP 0 461 761 B1 discloses rotation rate sensors inwhich a vibration gyro is excited on two axes which are aligned radiallywith respect to a major axis, for which purpose a primary and asecondary control loop having appropriate transducers are provided onthe vibration gyro. These control loops may include various analog anddigital circuits, with the analog circuits and the vibration gyro havingtolerances, so that adjustment is necessary, at least during theproduction of the rotation rate sensor. The individual circuits thenaccess the stored data during subsequent operation. Furthermore, it maybe necessary to match characteristics of the rotation rate sensor to therespectively intended purpose, for example by presetting parameter setsfor filters.

Storage and management of data such as this in the case of the rotationrate sensor according to the invention can be carried out particularlyadvantageously by the data being stored in a non-volatile memory whichcan be written to and by means being provided for reading the data fromthe non-volatile memory after switching on the rotation rate sensor. Thenon-volatile memory is preferably an EEPROM or a flash EEPROM.

One development of the rotation rate sensor according to the inventioncomprises the data being subdivided on the basis of its use into groups,and measures for data protection being taken for one group in each case.For data protection, provision is preferably made for a checksum to beformed over the data for in each case one group, to be stored in thenon-volatile memory and to be used for checking during reading.

The development makes it possible to write the data in each of theindividual groups to the non-volatile memory, and to edit it, in amutually independent manner, at different times. By way of example, theadjustment data can thus be stored in the non-volatile memory towardsthe end of the production process, while parameter sets which relate tothe use of the rotation rate sensor, for example the vehicle type inwhich the rotation rate sensor is intended to be installed, are storedlater, by the user.

All of the data which in any way governs the operation of the rotationrate sensor can be stored in the non-volatile memory. In particular,provision is made in the case of the rotation rate sensor according tothe invention for the adjustment data and/or parameter sets for filtersand/or value limits for self-testing of the rotation rate sensor to bestored.

Another development of the rotation rate sensor according to theinvention comprises a software emulation program also being stored inthe non-volatile memory.

The invention allows numerous embodiments. One of these will bedescribed in the following text and is illustrated schematically in anumber of figures in the drawing, in which:

FIG. 1 shows a block diagram of a rotation rate sensor according to theinvention, and

FIG. 2 shows, schematically, the content of the non-volatile memory.

The example of use shown in FIG. 1 represents a rotation rate sensor fora motor vehicle, having a vibration gyro 1 which is part of a sensormodule 2. This has a series of circuits for operation of the vibrationgyro and for evaluation of the signals from the vibration gyro,including, among other items, a microcomputer 3 which is connected viaan SPI bus 4 to a further microcomputer 5, which is also referred to inthe following text as a host. The rotation rate information is passedfrom here via a CAN bus driver 6 to a CAN bus 7 for passing onto othersystems in the motor vehicle. Data is stored in an EEPROM 8, is readwhen the rotation rate sensor is switched on, and is kept available inrandom access memories for the microcomputers 3 and 5 for access duringoperation.

Since this is not necessary for understanding of the invention, thevibration gyro 1 and the sensor module 2 will not be explained in anymore detail. Since the rotation rate sensor is relevant to safety,monitoring is provided for correct operation of the microcomputers 3, 5,in particular'the program execution.

FIG. 2 shows the data stored in the EEPROM 8, in a highly simplifiedform. For example, adjustment data items C1 to Cn are thus stored withan associated identifier IC and a checksum ChSC. Various parameters P1to Pn for setting filters are stored in the EEPROM 8, and these likewisehave an associated identifier IP and a checksum ChSP.

For safety reasons, monitoring is carried out continuously in therotation rate sensor during operation, for example by variables beingmonitored to determine whether they have overshot or undershot theirvalue ranges. The limits of these value ranges may differ from oneapplication to another. Limits L1 to Ln such as these are thereforelikewise stored with an associated identifier IL and a checksum ChSL inthe EEPROM 8. Finally, a program for software emulation is also storedin the EEPROM 8.

1.-9. (canceled)
 10. A rotation rate sensor comprising a vibration gyroand a plurality of circuits used for operating the vibration gyro andemitting a rotation rate signal, the plurality of circuits including anon-volatile memory being readable and writable to and storing dataincluding variable data, the plurality of circuits further comprisingmeans for reading the data from the non-volatile memory after switchingon the rotation rate sensor, wherein the data is subdivided into groupsbased on use of the data, the non-volatile memory including measures forsignal protection for each of the groups, the data in each of the groupsbeing readable and writable to independently of the data in the otherones of the groups, and a checksum is formed for the data in each of thegroups and stored in the volatile memory, the checksum being usable forchecking the data during reading.
 11. The rotation rate sensor of claim10, wherein said non-volatile memory comprises an EEPROM.
 12. Therotation rate sensor of claim 10, wherein said non-volatile memorycomprises a flash EEPROM.
 13. The rotation rate sensor of claim 10,wherein one of the groups includes adjustment data for the rotation ratesensor.
 14. The rotation rate sensor of claim 10, wherein one of thegroups includes parameter sets for filters.
 15. The rotation rate sensorof claim 10, wherein one of the groups includes value limits forself-testing of the rotation rate sensor.
 16. The rotation rate sensorof claim 10, wherein a software emulation program is also stored in thenon-volatile memory.